Typical hybrid power plants for a city bus include a combination power source that includes a battery pack and more recently a fuel cell stack. However, the fuel cell stacks which provide electric power for operating buses sustain daily decay in performance (voltage as a function of current density). Performance is recovered at the end of each day's service as part of a fuel cell power plant shutdown procedure. The performance of a fuel cell that provides motive power to a city bus is illustrated for the beginning of the day in the upper curve of FIG. 1 and at the end of a nine-hour day in the lower curve of FIG. 1.